This present invention relates generally to an apparatus and method for scanning and inspecting baggage. More particularly, the present invention relates to security screening systems for use at airports or other areas (e.g., court houses, buildings, arenas, seaports, hospitals, corporate facilities, government buildings, mailrooms, correctional facilities, nuclear power stations, special events, public areas, etc.) wherein a secure area is required.
In airport applications carry-on baggage inspection systems generally utilize a scan projection (SP) image for presentation to the operator. In most baggage inspection systems, scan projection images are created by moving an object under a fan beam of x-rays from a stationary x-ray source.
In some computed tomography (CT) imaging system configurations, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as an “imaging plane”. The x-ray beam passes through an object being imaged. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated radiation beam received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam intensity at each detector location. The intensity measurements from all the detectors are acquired separately to produce a transmission profile.
In third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged such that the angle at which the x-ray beam intersects the object constantly changes. A group of x-ray attenuation measurements (e.g., projection data), from the detector array at one gantry angle is referred to as a “view”. A “scan” of the object comprises a set of views made at different gantry angles, or view angles, during one revolution of the x-ray source and detector about the object or patient being imaged.
To perform a “helical” scan, the object is continually moved via a conveyor belt while the projection data for the prescribed number of slices is acquired. The helix mapped out by the fan beam yields projection data from which images in each prescribed slice may be reconstructed. Orthographic and scan projection SP-like images can be created from helical scan data by reconstruction of the entire volume, and projecting digitally through the reconstructed volume.
During the scanning of the object, potentially harmful X-ray beams are shielded by the structure of apparatus surrounding the conveyor belt and shielding means disposed at the apparatus entry and exit points (e.g., curtains disposed on the entry and exit points). In order to provide the necessary shielding an x-ray blocking material (e.g., lead, aluminum, carbon fibers or any other material that inhibits X-rays) is disposed in the apparatus structure and the curtains disposed at the entry and exit points.
However, these curtains may obstruct the flow of baggage on the conveyor as they may cause lighter objects (e.g., smaller bags, purses, carry on luggage, etc.) to tumble or even stop on the conveyor. This is exacerbated if such a device were to be used as an initial security screening measure at airport check in as typically smaller objects, purses, coats, shoes, laptops must be placed on the conveyor for x-ray screening.
In addition, these security devices are typically located proximate to personal screening devices wherein individuals desiring to be cleared through a security screening must place all of their belongings, metal objects, shoes, electronic devices etc. into a bin or tub designed to travel through the screening device. Thereafter, the individual walks though a personal screening device (e.g., metal detector) for clearance into the secure area.
Typically, these bins or tubs are located on an input side of a conveyor for the screening device and are left on the output side after the objects have been screened and picked up by their owner who has also cleared the security screening by passing through the personal screening device. Typically, the security screening location is set up as a barrier wherein entrance into the secure area is limited to access points wherein objects and personal must be screened or cleared prior to entry into the secure area. Therefore, once an individual is cleared through the personal screening they are free to retrieve their personal belongings as the output side of the security screening device. Thus and once their belongings are retrieved, the empty bins are left at the output side until an authorized security screening person picks up the empty bins and walks through the personal screening device back to the input side of the security screening device.
During this process of returning the empty bins to the input side of the security screening device, the personal security device is disabled or no longer usable for personal screening as one of the security personal must hand carry the empty bins to the input side. As might be expected this will slow the screening process of individuals wishing to enter the secure area as well as require manpower from the security personnel. Moreover, and in airports large bottlenecks may occur as passengers are cleared through the security checkpoint. Thus, any disruption to this process will exacerbate the bottleneck or slow down the security clearance.
Accordingly, it is desirable to provide an apparatus and method for returning empty bins used in a security screening process that does not adversely affect the security screening process. In addition, it is also desirable to provide an x-ray shielding means that does not interfere with the throughput of objects through the scanning system.